<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="https://cdn.bootcdn.net/ajax/libs/lodash.js/4.17.21/lodash.min.js"></script>
    <title>Document</title>
    <style>
        ul{
            width: 300px;
        }
        li{
            height: 40px;
            border-bottom: 1px solid #000;
        }
    </style>
</head>
<body>
    <div>
        <ul>
            <li>1</li>
            <li>1</li>
            <li>1</li>
            <li>1</li>
            <li>1</li>
            <li>1</li>
            <li>1</li>
            <li>1</li>
            <li>1</li>
            <li>1</li>
        </ul>
    </div>
    <script>
        const oLis = document.querySelectorAll('ul li')
        
        function enter (){
            console.log(1);
            this.style.background='red'
        }

        function leave (){
            console.log(2);
            this.style.background=''
        }

        const throttleEnter = _.throttle(enter,30,{
            leading:true,
            trailing:false
        })

        oLis.forEach((item)=>{
            item.onmouseenter=throttleEnter;
            item.onmouseleave=leave
        })
    </script>
</body>
</html>